The United Nations Conference on Environment and Development (UNCED), also known as the Rio Summit or Rio Conference or Earth Summit was a major United Nations conference held in Rio de Janeiro from 3 June to 14 June 1992.

Correct Option: C

The United Nations Conference on Environment and Development (UNCED), also known as the Rio Summit or Rio Conference or Earth Summit was a major United Nations conference held in Rio de Janeiro from 3 June to 14 June 1992.

Supersonic jet causes pollution by thinning of O₃ layer. The simple chlorine-chlorine monoxide cycle can only occur at high altitudes where there are enough free oxygen atoms to allow the second step in the chain to run. A number of evidences have accumulated to show that these reactions are indeed destroying small amounts of ozone at about 40 km above Earth. Other families of radicals also participate in catalytic cycles that destroy ozone- nitrogen oxides released by supersonic jets.

Correct Option: A

Supersonic jet causes pollution by thinning of O₃ layer. The simple chlorine-chlorine monoxide cycle can only occur at high altitudes where there are enough free oxygen atoms to allow the second step in the chain to run. A number of evidences have accumulated to show that these reactions are indeed destroying small amounts of ozone at about 40 km above Earth. Other families of radicals also participate in catalytic cycles that destroy ozone- nitrogen oxides released by supersonic jets.

Nitrification is not related to water pollution. It is a process through which atmospheric nitrogen (N₂) fixed in the form of nitrite and nitrate, it is one of the steps in nitrogen cycle which is included by nitrifying bacteria present in soil and root nodules of leguminous plants.

Correct Option: B

Nitrification is not related to water pollution. It is a process through which atmospheric nitrogen (N₂) fixed in the form of nitrite and nitrate, it is one of the steps in nitrogen cycle which is included by nitrifying bacteria present in soil and root nodules of leguminous plants.

Photochemical process is related to ozone formation. Ozone is formed as ultraviolet radiation from the sun breaks down oxygen in the atmosphere, O₂, into atomic oxygen with a single atom.
O₂ + sunlight ⇒ O + O
The excited free oxygen atom can bond with O₂ to form ozone.
O + O₂ ⇒ O₃

Correct Option: B

Photochemical process is related to ozone formation. Ozone is formed as ultraviolet radiation from the sun breaks down oxygen in the atmosphere, O₂, into atomic oxygen with a single atom.
O₂ + sunlight ⇒ O + O
The excited free oxygen atom can bond with O₂ to form ozone.
O + O₂ ⇒ O₃

The Ozone layer (present in Stratosphere) restricts the harmful ultraviolet radiations from penetrating into earth atmosphere. There are 3 types of UV radiation: UV-A, UV-B and UV-C in which except UV-A, other are dangerous for human health. They cause skin tumours. The ozone layers restricts the entry of UV-C and UV-B into earth' atmosphere.

Correct Option: D

The Ozone layer (present in Stratosphere) restricts the harmful ultraviolet radiations from penetrating into earth atmosphere. There are 3 types of UV radiation: UV-A, UV-B and UV-C in which except UV-A, other are dangerous for human health. They cause skin tumours. The ozone layers restricts the entry of UV-C and UV-B into earth' atmosphere.